Automatic telephone system



March 14, 1933.

' J. STICH AUTOMATIC TELEPHONE SYSTEM Filed Feb. 19, 1932 Jaharmln S'ITEh Patented Mar. 14, 1933 warren STATES- PATENT orricn .rormnnns srron, or BEnLrn-sInMnNss'rAnr, GERMANY, ASSIGNOR To SIEMENS & I-IALSKE AKTIENGESELLSGHAFT or WERNERWERK, or sIEMnnss'rAnr nnaa'nnn- LIN, GERMANY 1 AUTOMATIC TnLEriro ns s'rnM 2 Application filed February 19, 1932, Serial No. 594,066, and in Germany March 2,1931.

The present invention relates to a circuit arrangement for telephone systems with automatic operation and has for its object increased economy of such systems. This, ac-. cording to the invention, is achieved by using the devices which transmit impulses also to cut off the ringing current. I

An embodiment of the present invention is shown in the drawing. The subject matter relates to a private branch exchange in which a subscriber is able to connect-himself automatically to the exchange line AL over the shown group selector GVV, and in which incoming calls from the exchange, over the exchange line AL, are passed on by an operator to the required subscriber. In the arrangement shown, relay S serves in outgoing connections as an impulse repeater but oper ates as a ringing current cut of'frelay-in the case of incoming calls. 1

When, for example, the exchange line AL is seized over the group selector GW by a subscriber associated with the private branch exchange, relay C is energized over switch wiper c of the group selector GW, and by the actuation of its contacts 10 and 2c disconnects the lines 3 and 4 from the exchange line AL. At the seizure of the exchange line AL, relay S is energized in known manner over: earth, battery, contacts 270, 5111, winding I of relay S, switch wiper a of the group selector GIV, over the not shown subscribers line loop, switch wiper b of the group selector GW, winding III of relay S, earth. Relay S closes contact 'Z's with the result that a switching device is seized over the exchange line by completing the loop over the a-lead of the ez-1- change line AL, contacts 8A, 78, choke Dr, contact 9A, b-lead of the exchange line AL. Relay V1 is energized by the opening of con tact 6e and the closing of contact 108 over earth, contact 108, relay V1 battery, earth and, upon closing its contact 11011, sets up the following circuit: earth, contact 11121, relay V2, relay V1, battery, earth. Relay V2 is not energized in this circuit. Relay V1 causes contact 5211 to be opened. This removes the short-circuit for winding II of relay S. If the subscriber now sends out impulses with the object of setting the switches in the exchange, relay S will be cut off from battery at the first interruption at the subscribers station. Contact 7 8 is reopened and breaks the loop referred to above which extends over the choke Dr. V In addition, on the first release ofrelay S, contact 105 willbe opened and contact 68 closed, causing relay V2 to be energized over earth, contact 11121, relay V2, contact 68, battery, earth. Relay V2 opens contacts 12e2 and 13112. 7 I

The closing of contact 68 causes relay V1 to be short-circuited. The said relay V1, however, is not deenergized thereby since it remains energized due to the short-circuit and to the fact that it is constructed as a slow acting relay,until the circuit is re-closed after the impulse interruption, causing relay S to be re-energized. Relay S removes the short-circuit for relay V1 by opening contact 68, with the result that relay .Vl isconnected to battery afresh by the closing of contact 108. The closing of contact 108 shortcircuits relay V2. This relay V2 also is a slow-acting, relay and is not de -ener'gized in the short interval in which relay 1 S is ener gized during the circuit breaking at the subscribers station. Relay V2, as well as relay V 1, therefore, remains energized during an impulse series.

The circuit interruptionsat the subscrib ers station are transmitted by contact 78 to the exchange devices over the exchange line AL in the manner referred to above. Relay S is permanently re-energized at the end of the impulse series, with the consequence that 1 conver be energized in known manner by the ringing current from theex'changewhich sets up a locking circuit over winding II. ofrelay AR at the closing of contact 14mand, at the enquiry key, due to contacts 8A and 9A being same time,lights up the signal lamp SL, connected in parallel to winding II of relay AB;

The operator is heard after she has thrown her enquiry key, the contacts of which are represented by A in the drawing. The operators instrument BA is connected to the exchange line AL by the throwing over of this opened and contacts15A and 10A closed. In

addition, the locking circuit over winding'II- of relay AR and the circuit for the signallamp AL are cut off byopeningcontact 17A, and the circuit for relay P .is prepared, at the same tim'e,..when contact 18A is closed. The operator receives thej'calling exchangesub scribers instructions, who for example, wishes to set up a connectlon wlth a subscrlber to be reached over the line TL; The operator then inserts the plug St in the subscribers jack TKL, which energizes V relay I over earth, battery, resistance W, sleeve of the subscribers jack TKL, contact 19 of the plug St,

. windings I and II of relay P, contact 18A, earth. Relay P energizes and locks itself up over winding I at contact 20p and atcontact 28;! it opens the circuit for relay C to prevent the exchange line AL from being seized by a group selector, such as GW. The ring.

ing current from the inductor RM is sent to the subscriber by the closing of contact '21 and takes thefollowing path; inductor RM,

I contacts 21;), 5 01, winding I of relay S, contact 20, line 4, contact22'of plug St, contact 23 of ack TKL, a-lead of the subscribers line TL, contact 24 of jack TKL, contact 25 of plug St, line 3, contact 10, winding III of I. relay S, earth. When the called subscriber ing of. contact 260 1 is maintained energized over: earth, battery, contact 26111, windings II and I of relay S, contact 10, winding III of relay S, earth. The release of the con which the relay is used as an impulse repeat nection is carried out in ,a manner which is of no interest in this particular case.

As will be appreciated from the -above,'relay S is first used as an impulse repeating relay for outgoing calls whereas, in the case of incoming exchange connections, it operates as a ringing current cut oil relay. The subject matter of the presentinvention, however, is not restricted to the embodiment only in ing relay for outgoing calls and as a ringing current cut off relayln the case of -1ncom1ng connections.

subscriber to repeat impulses over the trunk line on outgoing calls and operated by an answering subscriber on incoming calls to disconnect signalling current.

3. In an automatic telephone system, a twoway trunk line extending from a branch exchange to a main exchange, a relay connected to said trunk line at the branch exchange end for repeating impulses to operate switches in the main exchange, an operators position at the branch exchange for answering calls from the main exchange and for extending the same to the wanted branch exchange subscriber, and means responsive to removal of the receiver by the wanted subscriber for operating said impulse repeating relay to disconnect the ringing current used for signalling.

4. In an automatic telephone system, a twoway trunk line, a relay bridged across the conductors of said trunk line, means controlled by a calling subscriber for operating said relay to repeat impulses to operate automatic switches at the distant end of said trunk line, means for connecting ringing current to signal a wanted subscriber when a call is received from the distant end of said trunk line, means responsive to the removal of the receiver by the wanted subscriber for completing a circuit over the conductors of said trunk line to operate said relay, and means responsive to the operation of said relay for disconnecting said ringing current.

5. In an automatic telephone system, a twoway trunk line. a relay associated with one end of said trunk line, means controlled by a calling subscriber for operating said relay to repeat impulses on outgoing calls, and means responsive to the removal of the receivcr by a wanted subscriber on incoming calls for operating said relay as a ring-cutoii relay. V

In witness whereof, I hereunto subscribe 1 y name this 19th day of January, A. D. 1932.

1 JOHANNES STICH. 

